It is well known that polyurethane flexible foams, which possess good physical properties, good mechanical properties and comfortable tactility, are widely used to prepare padding material, textile composite material and sound insulation material. Especially, in the padding industry, the auto parts, furniture and fitting made by polyurethane flexible foams possess the advantages of low-weight, good flexibility, good impact strength and comfortable tactility.
Generally, polyurethane flexible foams are produced by reacting isocyanate with polyols. The methods for preparing polyurethane flexible foams include one-step route and prepolymer route. For example, CN1130410C disclosed a method for preparing high resilience polyurethane flexible foams by reacting MDI composition with polyol composition. CN1047179C disclosed a method for preparing a polyurethane flexible foams by reacting high content 4,4′-MDI and the liquid variants thereof with polyol composition. CN100354330C disclosed a method for preparing middle-low density polyurethane foams by modified MDI-based isocyanate composition. CN1307226C disclosed a method for preparing polyurethane flexible foams by reacting isocyanate having high 4,4′-MDI content with polyoxyethylene-polyoxypropelene polyol.
Nevertheless, the mold temperature of the aforementioned methods for preparing polyurethane flexible foams shall be controlled at 65±5° C. If the mold temperature is too low, peel skin and/or coarse skin, which significantly reduce the quality of the foam surface, will be caused. In addition, the low mold temperature will slow the reaction rate, extend the demolding time which will reduce the production efficiency significantly.
As known to all, the process for preparing polyurethane flexible foams required a mold which can be heated, however, such kind of mold cost a lot of investment and energy. Therefore, the industry had committing itself to develop a new polyurethane flexible foam and the method for preparing the same to reduce the mold temperature, production time and energy consumption, as well as to obtain a polyurethane flexible foam processing good physical and mechanical properties.